Proton exchange membrane fuel cells (PEMFCs) can provide mobile and stationary power, but their adoption has been limited due to cost, low performance and inadequate durability. The membrane electrode assembly (MEA) is the heart of a PEMFC and it comprised of several components that affect the fuel cell's performance and efficiency. Among these components, the precious metal catalyst in the electrodes is a primary contributor to both the PEMFC's cost and its durability. PEMFC electrodes contain nanostructured platinum (Pt) dispersed on a porous activated-carbon support at ratios of about 10-60 wt. %. Because of its excellent electrical properties, good chemical and electrochemical stabilities, and high surface area, carbon black is typically used as a catalyst support. However, carbon black has limitations because its relatively inert surface interacts weakly with Pt nanoparticles, and thus they tend to migrate and agglomerate during fuel cell operation. In addition, the catalytic Pt nanoparticles can become trapped or isolated in the micropores of carbon black, making them electrochemically inaccessible.
During fuel cell operation, carbon black used as a catalyst support can corrode, forming oxygen containing functional groups on the surface that further weakens its interaction with platinum nanoparticles. The nanoparticles then detach from the support, which promotes both dissolution and agglomeration. Furthermore, carbon corrosion also decreases the catalyst layer thickness, lowers the electrical contact with the gas diffusion layer (GDL), and increases the fuel cell resistance. All of these consequences eventually result in loss of catalytic surface area, degradation of cell voltage, and reduction of fuel cell performance.